Power generation system

ABSTRACT

A power generation system includes: a hot water storage tank; a fuel cell apparatus configured to generate electric power; a heat supply apparatus provided separately from the fuel cell apparatus and configured to supply heat to the hot water storage tank; and a controller configured to operate the fuel cell apparatus in accordance with a predetermined first operation plan, and to operate the heat supply apparatus in accordance with a predetermined second operation plan. The controller is configured to perform, based on the first operation plan, second operation plan change control to operate the heat supply apparatus in a manner different from the predetermined second operation plan. The second operation plan change control is to reduce an output of the heat supply apparatus in accordance with an operation of the fuel cell apparatus, the operation being performed in accordance with the first operation plan.

TECHNICAL FIELD

The present invention relates to a power generation system including a fuel cell apparatus configured to generate electric power with use of a fuel gas and an oxidizing gas and to supply the electric power and heat.

BACKGROUND ART

A co-generation system is a system configured to generate and supply electric power to a consumer, thereby covering the consumer's electricity load, and to recover and store exhaust heat that is generated when generating the electric power, thereby covering the consumer's hot water load. As one of such co-generation systems, there is a known co-generation system that includes: a fuel cell; a hot water storage tank configured to store water that has been indirectly heated by heat generated when the fuel cell performs a power generation operation; and a water heater configured to heat the water that flows out of the hot water storage tank to a predetermined temperature (see Patent Literature 1, for example).

There is another known co-generation system configured to: store, in a heat storage tank, heat that is generated by the co-generation system; convert surplus electric power generated by a co-generation unit into heat by means of an electric heater; cover a shortfall of heat by means of a gas boiler; and cover a shortfall of electric power by means of commercial power supply (see Patent Literature 2, for example). The co-generation system is configured to: assume operating states and operation-stopped states based on pre-specified temporal changes in thermal and power demands while dividing one cycle into set periods; calculate a primary energy equivalent for each divided period by taking account of the amount of fuel supply necessary for operating the co-generation unit and the gas boiler, the amount of electric power to be supplied to cover a shortfall of electric power, and the amount of heat radiated from the system; and determine an optimal combination of an operating state and an operation-stopped state, in which combination the primary energy equivalent becomes minimum. The co-generation system is operated with the optimal combination.

CITATION LIST Patent Literature

-   PTL 1: Japanese Laid-Open Patent Application Publication No.     2007-248009 -   PTL 2: Japanese Laid-Open Patent Application Publication No.     2002-213303

SUMMARY OF INVENTION Technical Problem

An object of the present invention is to provide a power generation system in which a fuel cell apparatus and a heat supply apparatus are configured to supply heat to the same hot water storage tank and which makes it possible to reduce a possibility of decrease in energy efficiency.

Solution to Problem

In order to achieve the above object, a power generation system according to one aspect of the present invention includes: a hot water storage tank configured to store hot water; a fuel cell apparatus configured to generate electric power with use of a fuel gas and an oxidizing gas, and to supply heat to the hot water storage tank and output the electric power; a heat supply apparatus provided separately from the fuel cell apparatus and configured to supply heat to the hot water storage tank; and a controller configured to operate the fuel cell apparatus in accordance with a predetermined first operation plan, and to operate the heat supply apparatus in accordance with a predetermined second operation plan. The controller is configured to perform, based on the first operation plan, second operation plan change control to operate the heat supply apparatus in a manner different from the predetermined second operation plan. The second operation plan change control is to reduce an output of the heat supply apparatus in accordance with an operation of the fuel cell apparatus, the operation being performed in accordance with the first operation plan, to allow the operation of the fuel cell apparatus to be performed in accordance with the first operation plan.

The above configuration makes it possible to reduce a possibility of decrease in the energy efficiency of a power generation system in which a fuel cell apparatus and a heat supply apparatus are configured to supply heat to the same hot water storage tank.

Advantageous Effects of Invention

The present invention makes it possible to reduce a possibility of decrease in the energy efficiency of a power generation system in which a fuel cell apparatus and a heat supply apparatus are configured to supply heat to the same hot water storage tank.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing an example of a schematic configuration of a power generation system according to Embodiment 1.

FIG. 2 is a flowchart showing an example of a power generation system operating method according to Embodiment 1.

FIG. 3 is a block diagram showing an example of a schematic configuration of a power generation system according to a variation of Embodiment 1.

FIG. 4 is a block diagram showing an example of a schematic configuration of a power generation system according to Embodiment 2.

FIG. 5 is a flowchart showing an example of a power generation system operating method according to Embodiment 2.

FIG. 6 is a block diagram showing an example of a schematic configuration of a power generation system according to Embodiment 3.

FIG. 7 is a flowchart showing an example of a power generation system operating method according to Embodiment 3.

FIG. 8 is a flowchart showing an example of a power generation system operating method according to Embodiment 4.

FIG. 9 is a flowchart showing an example of a power generation system operating method according to a variation of Embodiment 4.

FIG. 10 is a schematic diagram showing a schematic configuration of a power generation system according to a working example.

FIG. 11 is a flowchart showing an example of a power generation system operating method according to the working example.

DESCRIPTION OF EMBODIMENTS

(Findings on Which Embodiments are Based)

Patent Literature 2 discloses that an operation plan is created for the entire co-generation system in which a fuel cell apparatus, a gas boiler, etc., are combined together. The technology disclosed in Patent Literature 2 is not applicable to a power generation system for which an operation plan is created for each of a fuel cell apparatus and a gas boiler separately. Moreover, in such a case where there is an operation plan specific to the gas boiler in addition to an operation plan specific to the fuel cell apparatus, the fuel cell apparatus and the gas boiler operate independently of each other. Consequently, there arises a problem in that the system operates in a manner to cause a decrease in energy efficiency, such as, generating hot water excessively since both of the fuel cell apparatus and the gas boiler operate.

In particular, fuel cell apparatuses supply both electric power and heat. Therefore, for example, in a case where electric power generated by a fuel cell apparatus cannot be sold to power companies, if the fuel cell apparatus is operated when there is no power demand, then the generated power cannot be utilized effectively, causing a decrease in efficiency. Thus, it is preferred that the fuel cell apparatus is operated in accordance with a power demand.

However, if heat generated by the fuel cell apparatus is not utilized at the same time as the generated electric power is utilized, then the efficiency of the fuel cell apparatus decreases. The generated heat is stored in a hot water storage tank and then used. If the hot water storage tank becomes full, then the heat generated by the fuel cell apparatus cannot be utilized effectively. Considering energy efficiency, there may be a case where the fuel cell apparatus is stopped when the hot water storage tank becomes full even if there is a power demand.

In view of the above, it is conceivable that the fuel cell apparatus is operated under the condition that there is a power demand and the hot water storage tank is not full. It is difficult to control a power demand. Therefore, it is necessary to suitably control the amount of storage water in the hot water storage tank so that the hot water storage tank will not become full during a period in which a power demand exists. Such control is strongly required particularly when heat supply to the hot water storage tank is performed not only by the fuel cell apparatus but also by another heat supply apparatus such as a gas boiler.

In view of the above problems, the inventors of the present invention have arrived at the idea of prioritizing an operation plan of a fuel cell apparatus (i.e., first operation plan) over an operation plan of a heat supply apparatus (i.e., second operation plan), that is, reducing the output of the heat supply apparatus in accordance with the operation of the fuel cell apparatus, the operation being performed in accordance with the first operation plan, to allow the operation of the fuel cell apparatus to be performed in accordance with the first operation plan. Thus, the output of the heat supply apparatus is reduced for prioritizing the operation of the fuel cell apparatus. This makes it possible to, for example, operate the fuel cell apparatus in an optimal time period so that the efficiency of the fuel cell apparatus will be maximized, and to reduce a possibility of decrease in energy efficiency.

Hereinafter, embodiments of the present invention are described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same reference signs, and a repetition of the same description is avoided. In the drawings, only the components necessary for describing the embodiments are shown, and the other components are omitted.

Embodiment 1

A first power generation system according to Embodiment 1 includes: a hot water storage tank configured to store hot water; a fuel cell apparatus configured to generate electric power with use of a fuel gas and an oxidizing gas, and to supply heat to the hot water storage tank and output the electric power; a heat supply apparatus provided separately from the fuel cell apparatus and configured to supply heat to the hot water storage tank; and a controller configured to operate the fuel cell apparatus in accordance with a predetermined first operation plan, and to operate the heat supply apparatus in accordance with a predetermined second operation plan. The controller is configured to perform, based on the first operation plan, second operation plan change control to operate the heat supply apparatus in a manner different from the predetermined second operation plan. The second operation plan change control is to reduce an output of the heat supply apparatus in accordance with an operation of the fuel cell apparatus, the operation being performed in accordance with the first operation plan, to allow the operation of the fuel cell apparatus to be performed in accordance with the first operation plan.

The above configuration makes it possible to reduce a possibility of decrease in the energy efficiency of a power generation system in which a fuel cell apparatus and a heat supply apparatus are configured to supply heat to the same hot water storage tank.

To “supply heat to the . . . hot water storage tank” refers to supplying heat generated within the apparatuses to the hot water storage tank in any given manner. Specifically, for example, hot water generated by the apparatuses may be directly supplied to and stored in the hot water storage tank. Alternatively, a heating medium may be heated within each apparatus, and hot water generated through heat exchange with the heating medium may be supplied to and stored in the hot water storage tank. Further alternatively, a heating medium heated within each apparatus may be supplied to the hot water storage tank, and hot water may be generated through heat exchange that is performed within the hot water storage tank between the heating medium and water.

Specifically, being “provided separately from the fuel cell apparatus” may be, for example, that the heat supply apparatus is disposed outside of a casing of the fuel cell apparatus. The fuel cell apparatus in a first casing and the heat supply apparatus in a second casing may be accommodated within a third casing together.

Specifically, to “operate the fuel cell apparatus in accordance with a predetermined first operation plan” may be, for example, as follows: a start-up time and a stop time of the fuel cell apparatus are set in advance; and the fuel cell apparatus is started up at the start-up time and the fuel cell apparatus is stopped at the stop time. Outputs of the fuel cell apparatus for respective time periods in one day may be set in advance, and in each time period, the fuel cell apparatus may be operated such that the output of the fuel cell apparatus becomes the set output.

Specifically, to “operate the heat supply apparatus in accordance with a predetermined second operation plan” may be, for example, as follows: a start-up time and a stop time of the heat supply apparatus are set in advance; and the fuel cell apparatus is started up at the start-up time and the heat supply apparatus is stopped at the stop time. Outputs of the heat supply apparatus for respective time periods in one day may be set in advance, and in each time period, the heat supply apparatus may be operated such that the output of the heat supply apparatus becomes the set output. Outputs of the heat supply apparatus for respective days in one week may be set in advance, and in each day, the heat supply apparatus may be operated such that the output of the heat supply apparatus becomes the set output. The predetermined second operation plan may allow the heat supply apparatus to operate independently of the operation of the fuel cell apparatus.

One specific example of “based on the first operation plan . . . operate the heat supply apparatus in a manner different from the predetermined second operation plan” may be to change the second operation plan so as to correspond to an actual operation of the fuel cell apparatus, the actual operation being performed in accordance with the first operation plan. Alternatively, without changing the second operation plan, the operation of the heat supply apparatus may be performed in a manner different from the predetermined second operation plan temporarily so as to correspond to an actual operation of the fuel cell apparatus, the actual operation being performed in accordance with the first operation plan. As another alternative, the second operation plan may be changed based on information about the first operation plan. As yet another alternative, without changing the second operation plan, the operation of the heat supply apparatus may be performed in a manner different from the predetermined second operation plan temporarily based on information about the first operation plan.

Specifically, to “allow the operation of the fuel cell apparatus to be performed in accordance with the first operation plan” may mean a case where the operation of the fuel cell apparatus in accordance with the first operation plan is fully realized. If the operation of the fuel cell apparatus in accordance with the first operation plan cannot be fully realized, then to “allow the operation of the fuel cell apparatus to be performed in accordance with the first operation plan” may mean a case of reducing the output of the heat supply apparatus, thereby allowing the operation of the fuel cell apparatus to be performed in a manner closely similar to the first operation plan (e.g., in such a manner as to allow the operating time and the amount of generated heat to be closely similar to those determined by the first operation plan).

Specifically, to “reduce an output of the heat supply apparatus” may be, for example, to reduce the output of the heat supply apparatus without stopping the operation of the heat supply apparatus, or to stop the operation of the heat supply apparatus.

A second power generation system according to Embodiment 1 is configured such that, in the first power generation system, the second operation plan change control is to reduce the output of the heat supply apparatus when the fuel cell apparatus starts up.

Specifically, “when the fuel cell apparatus starts up” means, for example, that the reduction of the output of the heat supply apparatus may be performed in conjunction with the start-up of the fuel cell apparatus; the reduction of the output of the heat supply apparatus may be performed at the same time as the start-up of the fuel cell apparatus; the reduction of the output of the heat supply apparatus may be performed a predetermined time before the start-up of the fuel cell apparatus; or the reduction of the output of the heat supply apparatus may be performed a predetermined time after the start-up of the fuel cell apparatus. The start-up of the fuel cell may be performed at the beginning, in the middle, or at the end of a start-up sequence.

A third power generation system according to Embodiment 1 is configured such that at least one of the first and second power generation systems further includes a load measuring unit configured to measure an amount of electric power and an amount of heat that are consumed by a user of the power generation system. In the third power generation system, the controller: creates the first operation plan based on the amount of electric power and the amount of heat that have been measured by the load measuring unit, and stores the first operation plan; and creates the second operation plan based on an operation period set by the user, and stores the second operation plan.

[Apparatus Configuration]

FIG. 1 is a block diagram showing an example of a schematic configuration of a power generation system according to Embodiment 1.

A power generation system 130 according to Embodiment 1 includes: a hot water storage tank 10; a fuel cell apparatus 20; a heat supply apparatus 30; and a controller 40.

The hot water storage tank 10 stores hot water (high-temperature water in liquid form).

The fuel cell apparatus 20 generates electric power with use of a fuel gas and an oxidizing gas. The fuel cell apparatus 20 outputs the electric power, and supplies heat to the hot water storage tank. The fuel cell included in the fuel cell apparatus 20 may be of any type. Specific examples of the fuel cell include a polymer electrolyte fuel cell (PEFC), a solid oxide fuel cell (SOFC), and a phosphoric-acid fuel cell.

The heat supply apparatus 30 is provided separately from the fuel cell apparatus 20, and supplies heat to the hot water storage tank 10. The heat supply apparatus 30 has a different heat supply mechanism from that of the fuel cell. As one specific example, the heat supply apparatus 30 may be a boiler configured to generate hot water by using, for example, a fuel gas or kerosene. Alternatively, the heat supply apparatus 30 may be, for example, a solar panel configured to generate hot water by using solar light.

A method of supplying heat to the hot water storage tank 10 from the fuel cell apparatus 20 and the heat supply apparatus 30 can be implemented in various modes.

Specifically, one exemplary mode is as follows. The hot water storage tank 10 includes: a first inlet through which hot water (in this example, heated municipal water) supplied from the fuel cell apparatus 20 flows into the hot water storage tank 10; a second inlet through which hot water (in this example, heated municipal water) supplied from the heat supply apparatus 30 flows into the hot water storage tank 10; a third inlet through which municipal water from the outside of the power generation system flows into the hot water storage tank 10; a first outlet through which the municipal water stored in the hot water storage tank 10 is discharged into the fuel cell apparatus 20; a second outlet through which the municipal water stored in the hot water storage tank 10 is discharged into the heat supply apparatus 30; and a hot water outlet through which hot water is discharged. In this case, the fuel cell apparatus 20 generates hot water by heating the municipal water supplied from the hot water storage tank 10. The heat supply apparatus 30 generates hot water by heating the municipal water supplied from the hot water storage tank 10. The hot water is discharged through the hot water outlet, and is used by a user.

Another exemplary mode is as follows. The hot water storage tank 10 includes: a first inlet through which a first heating medium discharged from the fuel cell apparatus 20 flows into the hot water storage tank 10; a first heat exchanger for allowing the first heating medium to exchange heat with municipal water stored in the hot water storage tank 10; a first outlet through which the first heating medium is discharged; a second inlet through which a second heating medium discharged from the heat supply apparatus 30 flows into the hot water storage tank 10; a second heat exchanger for allowing the second heating medium to exchange heat with municipal water stored in the hot water storage tank 10; a second outlet through which the second heating medium is discharged; a third inlet through which municipal water from the outside of the power generation system flows into the hot water storage tank 10; and a third outlet through which hot water is discharged. In this case, the fuel cell apparatus 20 heats the first heating medium and supplies the resultant high-temperature first heating medium to the first heat exchanger, and the heat supply apparatus 30 heats the second heating medium and supplies the resultant high-temperature second heating medium to the second heat exchanger. The municipal water supplied through the third inlet is heated at the first heat exchanger and the second heat exchanger, and thereby becomes hot water. The hot water is discharged through the third outlet, and is used by a user. Specifically, for example, each heating medium may be water, non-freezing water, or a different kind of liquid. As one specific example, each heat exchanger may be configured as coiled piping formed within the hot water storage tank 10.

Yet another exemplary mode is as follows. The hot water storage tank 10 includes: a first inlet through which hot water supplied from the fuel cell apparatus 20 flows into the hot water storage tank 10; a second inlet through which hot water supplied from the heat supply apparatus 30 flows into the hot water storage tank 10; and an outlet through which hot water is discharged. In this case, the fuel cell apparatus 20 generates hot water, for example, by heating municipal water supplied from the outside of the power generation system. Also, the heat supply apparatus 30 generates hot water, for example, by heating municipal water supplied from the outside of the power generation system. The hot water is discharged through the outlet, and is used by a user.

Yet another exemplary mode is as follows. The hot water storage tank 10 includes: an inlet through which a mixture of hot water supplied from the fuel cell apparatus 20 and hot water supplied from the heat supply apparatus 30 flows into the hot water storage tank 10; and an outlet through which hot water is discharged. In this case, the fuel cell apparatus 20 generates hot water, for example, by heating municipal water supplied from the outside of the power generation system. Also, the heat supply apparatus 30 generates hot water, for example, by heating municipal water supplied from the outside of the power generation system. The hot water is discharged through the outlet, and is used by a user.

In yet another exemplary mode, the first heat exchanger and the second heat exchanger may be provided outside of the hot water storage tank 10.

The method of supplying heat from the fuel cell apparatus 20 to the hot water storage tank 10 may be the same as or different from the method of supplying heat from the heat supply apparatus 30 to the hot water storage tank 10. For example, the heat supplying method may include direct heat supply and indirect heat supply. In the indirect heat supply, for example, heat generated from the apparatuses may be indirectly supplied to the hot water storage tank through the heating media and the heat exchangers. In the direct heat supply, for example, hot water is generated by the apparatuses and the generated hot water may be directly supplied to the hot water storage tank 10.

The controller 40 operates the fuel cell apparatus 20 in accordance with a predetermined first operation plan, and operates the heat supply apparatus 30 in accordance with a predetermined second operation plan. The controller 40 is configured to perform, based on the first operation plan, second operation plan change control to operate the heat supply apparatus 30 in a manner different from the predetermined second operation plan. The second operation plan change control is to reduce the output of the heat supply apparatus 30 in accordance with the operation of the fuel cell apparatus 20, the operation being performed in accordance with the first operation plan, to allow the operation of the fuel cell apparatus 20 to be performed in accordance with the first operation plan. Specifically, for example, the operation herein may include start-up and stop.

The controller 40 may be any device, so long as the controller 40 implement control functions. For example, the controller 40 includes an arithmetic processing unit and a storage unit storing control programs. Examples of the controller 40 include a microcontroller and a PLC (Programmable Logic Controller). Examples of the arithmetic processing unit include an MPU and a CPU. The storage unit is a memory, for example. The controller 40 may be configured as a single controller performing centralized control, or may be configured as multiple controllers performing distributed control in cooperation with each other.

The controller 40 may include a first controller configured to control the fuel cell apparatus 20 and a second controller configured to control the heat supply apparatus 30. The first controller and the second controller may be realized by the controller 40 configured as a single controller.

[Operating Method]

FIG. 2 is a flowchart showing an example of a power generation system operating method according to Embodiment 1. FIG. 2 shows a method of operating the second power generation system according to Embodiment 1. The operating method may be executed through control by the controller 40.

In the power generation system 130, when the fuel cell apparatus 20 starts up (step S101), the output of the heat supply apparatus 30 is reduced (step S102). Specifically, for example, step S101 and step S102 may be performed in conjunction with each other. Step S101 and step S102 may be performed at the same time. Step S102 may be performed a predetermined time before step S101. Step S102 may be performed a predetermined time after step S101. Step S101 may be performed at the beginning, in the middle, or at the end of a start-up sequence. Step S102 may be performed without causing any changes in the second operation plan.

[Variation]

FIG. 3 is a block diagram showing an example of a schematic configuration of a power generation system according to a variation of Embodiment 1. The configuration of a power generation system 140 according to the present variation is the same as that of the power generation system 130 shown in FIG. 1, except that the power generation system 140 includes a power load measuring unit 46 and a thermal load measuring unit 47. Therefore, common components between FIG. 1 and FIG. 3 are denoted by the same names and reference signs, and a detailed description of such components is omitted.

The power load measuring unit 46 measures the amount of electric power consumed by a user of the power generation system. The power load measuring unit 46 outputs the measured amount of electric power to the controller 40. Specifically, for example, the power load measuring unit 46 may be configured as a current sensor. For example, the current sensor may be disposed such that the current sensor is closer to a commercial power system than a point where the commercial power system and the electric power output of the fuel cell apparatus are connected.

The thermal load measuring unit 47 measures the amount of heat consumed by the user of the power generation system. The thermal load measuring unit 47 outputs the measured amount of heat to the controller 40. Specifically, for example, the thermal load measuring unit 47 may include: a flowmeter disposed at an outlet of the hot water storage tank 10, through which outlet the user is supplied with hot water; and a temperature sensor.

In the present variation, the controller 40 creates the first operation plan based on the amount of electric power measured by the power load measuring unit 46 and the amount of heat measured by the thermal load measuring unit 47, and stores the created first operation plan. Also, the controller 40 creates the second operation plan based on an operation period set by the user, and stores the created second operation plan. The user may set the operation period by using an operating unit which is not shown.

Embodiment 2

A first power generation system according to Embodiment 2 is configured such that, in the second power generation system according to Embodiment 1, the controller includes: a first controller configured to store the first operation plan and to start up and stop the fuel cell apparatus in accordance with the stored first operation plan; and a second controller configured to store the second operation plan and to operate the heat supply apparatus in accordance with the stored second operation plan. The first controller is configured to transmit a signal indicating that the fuel cell apparatus starts up. The second operation plan change control is that, in a case where the second controller has received the signal indicating that the fuel cell apparatus starts up, the second controller reduces the output of the heat supply apparatus. The second power generation system according to Embodiment 1 may be a power generation system according to any mode described in Embodiment 1.

A second power generation system according to Embodiment 2 is configured such that, in the first power generation system according to Embodiment 2, the signal indicating that the fuel cell apparatus starts up is transmitted at a point that is a first time before the fuel cell apparatus starts up.

A third power generation system according to Embodiment 2 is configured such that, in the first power generation system according to Embodiment 2, the signal indicating that the fuel cell apparatus starts up is transmitted when the fuel cell apparatus starts up.

A fourth power generation system according to Embodiment 2 is configured such that at least one of the first to third power generation systems according to Embodiment 2 further includes a load measuring unit configured to measure an amount of electric power and an amount of heat that are consumed by a user of the power generation system. The controller: creates the first operation plan based on the amount of electric power and the amount of heat that have been measured by the load measuring unit, and stores the first operation plan; and creates the second operation plan based on an operation period set by the user, and stores the second operation plan.

[Apparatus Configuration]

FIG. 4 is a block diagram showing an example of a schematic configuration of a power generation system according to Embodiment 2. The configuration of a power generation system 150 according to the present embodiment is the same as that of the power generation system 130 shown in FIG. 1, except that the controller 40 is replaced by a first controller 41 and a second controller 42. Therefore, common components between FIG. 1 and FIG. 4 are denoted by the same names and reference signs, and a detailed description of such components is omitted.

In the present embodiment, the controller includes the first controller 41 and the second controller 42.

The first controller 41 stores the first operation plan, and starts up and stops the fuel cell apparatus 20 in accordance with the stored first operation plan. The first controller 41 transmits a signal indicating that the fuel cell apparatus 20 starts up.

The second controller 42 stores the second operation plan, and operates the heat supply apparatus 30 in accordance with the stored second operation plan. In a case where the second controller 42 has received the signal indicating that the fuel cell apparatus 20 starts up, the second controller 42 reduces the output of the heat supply apparatus 30. The second controller 42 may receive the signal directly from the first controller 41, or may receive the signal indirectly.

Any device implementing control functions may serve as the first controller 41 and the second controller 42. The controllers include, for example, an arithmetic processing unit and a storage unit storing control programs. For example, a microcontroller or a PLC (Programmable Logic Controller) serves as the first controller 41 and the second controller 42. Examples of the arithmetic processing unit include an MPU and a CPU. The storage unit is a memory, for example. Each of the first controller 41 and the second controller 42 may be configured as a single controller performing centralized control, or may be configured as multiple controllers performing distributed control in cooperation with each other.

Since the fourth power generation system according to Embodiment 2 is suitably configurable with reference to FIG. 3 and FIG. 4, a detailed description of the fourth power generation system is omitted.

[Operating Method]

FIG. 5 is a flowchart showing an example of a power generation system operating method according to Embodiment 2. FIG. 5 shows a method of operating the first power generation system according to Embodiment 2.

When starting up the fuel cell apparatus 20 in accordance with the first operation plan, the first controller 41 transmits a signal indicating that the fuel cell apparatus 20 starts up (step S201). The signal indicating that the fuel cell apparatus 20 starts up may be transmitted at a point that is a first time before the fuel cell apparatus 20 starts up, or may be transmitted at the same time as the fuel cell apparatus 20 starts up. The first time may be calculated by the first controller 41 with use of data including the amount of hot water stored in the hot water storage tank 10 and an air temperature so that the operation of the fuel cell apparatus 20 can be performed in accordance with the first operation plan.

Then, the second controller 42 receives the signal indicating that the fuel cell apparatus 20 starts up (step S202).

Thereafter, the second controller 42 reduces the output of the heat supply apparatus 30 (step S203).

Embodiment 3

A first power generation system according to Embodiment 3 is configured such that the second power generation system according to Embodiment 1 further includes a detector configured to detect a start-up of the fuel cell apparatus and to transmit a signal indicating that the start-up of the fuel cell apparatus has been detected. The controller includes: a first controller configured to store the first operation plan and to start up and stop the fuel cell apparatus in accordance with the stored first operation plan; and a second controller configured to store the second operation plan and to operate the heat supply apparatus in accordance with the stored second operation plan. In the first power generation system according to Embodiment 3, the second operation plan change control is that, in a case where the second controller has received the signal indicating that the start-up of the fuel cell apparatus has been detected, the second controller reduces the output of the heat supply apparatus. Here, the second power generation system according to Embodiment 1 and its components may be a power generation system according to any mode described in Embodiment 1 and its components.

A second power generation system according to Embodiment 3 is configured such that the first power generation system according to Embodiment 3 further includes a load measuring unit configured to measure an amount of electric power and an amount of heat that are consumed by a user of the power generation system. In the second power generation system according to Embodiment 3, the controller: creates the first operation plan based on the amount of electric power and the amount of heat that have been measured by the load measuring unit, and stores the first operation plan; and creates the second operation plan based on an operation period set by the user, and stores the second operation plan.

[Apparatus Configuration]

FIG. 6 is a block diagram showing an example of a schematic configuration of a power generation system according to Embodiment 3. The configuration of a power generation system 160 according to the present embodiment is the same as that of the power generation system 130 shown in FIG. 1, except that the controller 40 is replaced by the first controller 41 and the second controller 42 and the power generation system 160 further includes a detector 48. Therefore, common components between FIG. 1 and FIG. 6 are denoted by the same names and reference signs, and a detailed description of such components is omitted.

The detector 48 detects a start-up of the fuel cell apparatus, and transmits a signal indicating that the start-up of the fuel cell apparatus has been detected. Specifically, the detector 48 may be configured as a temperature detector, a pressure detector, or a flow rate detector, for example.

In the present embodiment, the controller includes the first controller 41 and the second controller 42.

The first controller 41 stores the first operation plan, and starts up and stops the fuel cell apparatus 20 in accordance with the stored first operation plan.

The second controller 42 stores the second operation plan, and operates the heat supply apparatus 30 in accordance with the stored second operation plan. In a case where the second controller 42 has received the signal indicating that the start-up of the fuel cell apparatus has been detected, the second controller 42 reduces the output of the heat supply apparatus 30. The second controller 42 may receive the signal directly from the detector 48, or may receive the signal indirectly.

Any device implementing control functions may serve as the first controller 41 and the second controller 42. The controllers include, for example, an arithmetic processing unit and a storage unit storing control programs. For example, a microcontroller or a PLC (Programmable Logic Controller) serves as the first controller 41 and the second controller 42. Examples of the arithmetic processing unit include an MPU and a CPU. The storage unit is a memory, for example. Each of the first controller 41 and the second controller 42 may be configured as a single controller performing centralized control, or may be configured as multiple controllers performing distributed control in cooperation with each other.

Since the second power generation system according to Embodiment 3 is suitably configurable with reference to FIG. 3 and FIG. 4, a detailed description of the second power generation system is omitted.

[Operating Method]

FIG. 7 is a flowchart showing an example of a power generation system operating method according to Embodiment 3. FIG. 7 shows a method of operating the first power generation system according to Embodiment 3.

When the detector 48 detects a start-up of the fuel cell apparatus 20, the detector 48 transmits a signal indicating that the start-up of the fuel cell apparatus 20 has been detected (step S301).

Then, the second controller 42 receives the signal indicating that the start-up of the fuel cell apparatus 20 has been detected (step S302).

Thereafter, the second controller 42 reduces the output of the heat supply apparatus 30 (step S303).

Embodiment 4

A first power generation system according to Embodiment 4 is configured such that, in the first power generation system according to Embodiment 1, the second operation plan change control is that, in a case where the first operation plan has been changed, the controller changes the second operation plan based on the changed first operation plan.

Specifically, the “case where the first operation plan has been changed” includes, for example, a case where the start-up time of the fuel cell apparatus has been newly set. The first operation plan may be changed, for example, automatically by the controller or manually by a user via an operating unit (not shown). To be more specific, for example, in a case where the power generation system includes a power load measuring unit and a thermal load measuring unit, the controller may change the first operation plan based on the amount of consumed electric power and the amount of consumed heat that are received from the power load measuring unit and the thermal load measuring unit. The first operation plan may be changed in accordance with inputs that are made by a user via an input unit or the like. The user may directly change the first operation plan via an input unit or the like.

Specifically, “changes the second operation plan” may be, for example, in a case where an operation period of the heat supply apparatus is set as the second operation plan, to shift the operation period of the heat supply apparatus such that the output of the heat supply apparatus is reduced in an operation period of the fuel cell apparatus. Alternatively, in a predetermined period included in the operation period of the heat supply apparatus, the operation of the heat supply apparatus may be stopped or the output of the heat supply apparatus may be reduced. The controller may store the changed second operation plan.

A second power generation system according to Embodiment 4 is configured such that, in the first power generation system according to Embodiment 3, the controller includes: a first controller configured to store the first operation plan and to start up and stop the fuel cell apparatus in accordance with the stored first operation plan; a second controller configured to store the second operation plan and to operate the heat supply apparatus in accordance with the stored second operation plan. In the second power generation system according to Embodiment 4, the first controller is configured to transmit information about the changed first operation plan in the case where the first operation plan has been changed, and the second operation plan change control is that the second controller changes the second operation plan when the second controller has received the information about the changed first operation plan.

Specifically, for example, the “information about the changed first operation plan” may be the start-up time of the fuel cell apparatus, or may be the amount of heat to be generated by the fuel cell apparatus, or may be the start-up time and stop time of the fuel cell apparatus and the amount of heat to be generated by the fuel cell apparatus.

The second controller may store the changed second operation plan.

A third power generation system according to Embodiment 4 is configured such that at least one of the first and second power generation systems according to Embodiment 3 further includes a load measuring unit configured to measure an amount of electric power and an amount of heat that are consumed by a user of the power generation system. The controller: creates the first operation plan based on the amount of electric power and the amount of heat that have been measured by the load measuring unit, and stores the first operation plan; and creates the second operation plan based on an operation period set by the user, and stores the second operation plan.

[Apparatus Configuration]

The apparatus configuration of the power generation systems according to Embodiment 4 may be, for example, the same as that shown in at least one of Embodiment 1 (FIG. 1) and Embodiment 2 (FIG. 4). Therefore, common components between FIG. 1 and FIG. 4 are denoted by the same reference signs and names, and a detailed description of such components is omitted. Specifically, the configuration of the first power generation system according to Embodiment 4 may be the same as, for example, the configuration shown in Embodiment 1 (FIG. 1); the configuration of the second power generation system according to Embodiment 4 may be the same as, for example, the configuration shown in Embodiment 2 (FIG. 4); and the configuration of the third power generation system according to Embodiment 4 may be the same as, for example, the configuration shown in the variation of Embodiment 1 (FIG. 3).

[Operating Method]

FIG. 8 is a flowchart showing an example of a power generation system operating method according to Embodiment 4. FIG. 8 shows a method of operating the first power generation system according to Embodiment 4. The operating method may be executed through control by the controller 40.

In the power generation system according to the present embodiment, when the first operation plan is changed (step S401), the controller 40 changes the second operation plan based on the changed first operation plan (step S402).

[Variation]

FIG. 9 is a flowchart showing an example of a power generation system operating method according to a variation of Embodiment 4. FIG. 9 shows a method of operating the second power generation system according to Embodiment 4.

In the power generation system according to the present variation, when the first operation plan is changed (step S501), the first controller 41 outputs information about the changed first operation plan (step S502). The second controller 42 receives the information about the changed first operation plan (step S503). Then, the second controller 42 changes the second operation plan based on the information about the changed first operation plan, and stores the changed second operation plan (step S504).

Working Example

FIG. 10 is a schematic diagram showing a schematic configuration of a power generation system according to a working example.

As shown in FIG. 10, a power generation system 100 according to the working example includes: a fuel cell apparatus 110 configured to generate electric power with use of a fuel gas and an oxidizing gas, and to supply the electric power and heat; a hot water storage tank 103 configured to store water that has absorbed heat of the fuel cell apparatus 110; and a heat supply apparatus 101 configured to supply heat to the water in the hot water storage tank 103. The power generation system 100 further includes: a first controller 120 configured to control at least start-up and stop of the fuel cell apparatus 110 in accordance with a predetermined operation plan of the fuel cell apparatus 110; and a second controller 121 configured to control at least start-up and stop of the heat supply apparatus 101 in accordance with a predetermined operation plan of the heat supply apparatus 101. The second controller 121 also controls the output of the heat supply apparatus 101. In a case where the second controller 121 has received, from the first controller 120, information indicating that the fuel cell apparatus 110 starts up, the second controller 121 performs control to reduce the output of the heat supply apparatus 101. Here, reducing the output of the heat supply apparatus 101 includes stopping the heat supply apparatus 101, i.e., reducing the output of the heat supply apparatus 101 to zero.

Since a known fuel cell apparatus may be used as the fuel cell apparatus 110, the fuel cell apparatus 110 will not be described in detail, but a brief description of the fuel cell apparatus 110 is given below. The fuel cell apparatus 110 includes: a fuel cell 111 and accessory devices (not shown) for allowing the fuel cell 111 to function. Examples of the accessory devices include: a fuel gas supply device configured to supply a fuel gas to the fuel cell 111; an oxidizing gas supply device configured to supply an oxidizing gas to the fuel cell 111; a cooling system configured to cool down the fuel cell 111; and a power conditioner configured to extract electric power generated by the fuel cell 111 and to supply the electric power to the outside (to an external load).

A known fuel cell may be used as the fuel cell 111. Examples of fuel cells usable as the fuel cell 111 include a polymer electrolyte fuel cell, a solid oxide fuel cell, and a phosphoric-acid fuel cell.

The heat supply apparatus 101 is configured to combust a combustion fuel gas, thereby generating heat for covering a thermal demand from a heat load. The heat supply apparatus 101 combusts a combustion fuel gas supplied from a combustion fuel gas supply device (not shown) by using an oxidizing gas (e.g., air) supplied from an oxidizing gas supply device (not shown). The amount of combustion of the combustion fuel gas at the heat supply apparatus 101 is controlled, for example, by controlling the supply amount of the combustion fuel gas. The heat supply apparatus 101 is, for example, a boiler. Examples of the heat load include a hot water supply system, a hot-water heating system, and shower.

The hot water storage tank 103 is an apparatus configured to store hot water that has been heated by exhaust heat transmitted from the fuel cell apparatus 110 via a first heat transmission mechanism 106 and exhaust heat transmitted from the heat supply apparatus 101 via a second heat transmission mechanism 107. The hot water stored in the hot water storage tank 103 is supplied to the aforementioned heat load through a heat supply passage (not shown). The hot water storage tank 103 is supplied with water from a water source (e.g., municipal water) through a water supply passage (not shown). It should be noted that the first heat transmission mechanism 106 and the hot water storage tank 103 form the aforementioned cooling system configured to cool down the fuel cell apparatus 110. The first heat transmission mechanism 106 and the second heat transmission mechanism 107 may be configured in any manner. For example, each heat transmission mechanism may be configured as a heating medium circulation mechanism that causes a heating medium to circulate, or as a heating medium moving mechanism that causes a heating medium to move in one direction. The heating medium circulation mechanism includes, for example, a heating medium circulation passage and a pump that causes the heating medium to circulate. The heating medium moving mechanism includes, for example, a heating medium moving passage and a pump that causes the heating medium to move. As the heating medium, water (hot water) stored in the hot water storage tank 103 or a heating medium different from the water (hot water) stored in the hot water storage tank 103 may be used, for example. In the latter case, for example, a heat exchanger is provided, the heat exchanger causing the heating medium that moves (circulates) through the heating medium moving passage and water (hot water) that is stored in the hot water storage tank 103 to exchange heat with each other.

An operating unit 109 is operated by a consumer 105, i.e., by a user, and is configured to transmit settings made by the user to the first controller 120 and the second controller 121 by wired or wireless communication.

The power generation system 100 may include a load measuring unit (not shown) configured to exchange information with the first controller 120. The load measuring unit measures the amount of electric power and the amount of heat that have been consumed by the consumer provided with the fuel cell apparatus 110. Specifically, the load measuring unit includes: a thermal load measuring unit (not shown) configured to measure the amount of heat of hot water supplied from the hot water storage tank 103 to a faucet or the like; and an electric power measuring unit (not shown) configured to measure the amount of electric power consumed by the consumer.

The first controller 120 is configured to create an operation plan of the fuel cell apparatus 110 in advance based on, for example, setting information such as an operation-prohibited period sent from the operating unit 109 and thermal and power demands measured by the load measuring unit, thereby setting a start-up time and a stop time of the fuel cell apparatus 110. The first controller 120 causes the fuel cell apparatus 110 to start up at the start-up time set in the operation plan and to stop the fuel cell apparatus 110 at the stop time set in the operation plan. The second controller 121 controls the output of the heat supply apparatus 101.

In addition, the second controller 121 causes the heat supply apparatus 101 to start up and stop in accordance with an operation plan of the heat supply apparatus 101, which is set in advance. The second controller 121 may receive, from the operating unit 109, information about at least one of an operation period and an operation mode that are set by the user, and may create an operation plan based on the operation period. Alternatively, the operation period set by the user may be directly used as the operation plan.

The first controller 120 and the second controller 121 may be arranged at any positions. For example, the first controller 120 and the second controller 121 may be arranged separately from the fuel cell apparatus 110 and the heat supply apparatus 101. Alternatively, the first controller 120 and the second controller 121 may be arranged within the fuel cell apparatus 110. Further alternatively, the first controller 120 and the second controller 121 may be arranged within the heat supply apparatus 101.

Each of the first controller 120 and the second controller 121 may be any device, so long as the device is configured to implement control functions. For example, each controller may be configured as a microcontroller, an MPU, a PLC (Programmable Logic Controller), or a logic circuit. Each of the first controller 120 and the second controller 121 may be configured as a single controller performing centralized control, or may be configured as multiple independent controllers performing distributed control in cooperation with each other.

[Operations of Power Generation System]

Next, a description is given of an example of operations of the power generation system 100 configured as described above.

FIG. 11 is a flowchart showing an example of control of the power generation system of FIG. 10. The control is performed by the first controller 120 and the second controller 121. The control is repeated at predetermined intervals.

As shown in FIG. 11, when the control starts, the second controller 121 determines whether information indicating that the fuel cell apparatus 110 starts up has been received from the first controller 120 (step S1).

If information indicating that the fuel cell apparatus 110 starts up has been received from the first controller 120 (YES in step S1), the second controller 121 reduces the output of the heat supply apparatus 101 (step S2). Specifically, in order to reduce the amount of combustion at the heat supply apparatus 101, the second controller 121 reduces the amount of combustion gas to be supplied.

On the other hand, if the second controller 121 has not received information indicating that the fuel cell apparatus 110 starts up (NO in step S1), the output of the heat supply apparatus 101 is maintained.

It should be noted that, in step S2, the second controller 121 may control the output of the heat supply apparatus 101 to be less than the output thereof determined by the operation plan.

A first predetermined time before the start-up of the fuel cell apparatus 110, the first controller 120 may transmit, to the second controller 121, information indicating that the fuel cell apparatus 110 starts up. The first predetermined time herein is a time that is necessary to prevent the hot water storage tank 103 from becoming a full storage state (i.e., a state where the temperature of water in the hot water storage tank 103 has increased to such a degree that the water can no longer absorb the heat of the fuel cell apparatus 110), thereby allowing heat generated due to the power generation by the fuel cell apparatus 110 to be absorbed by the water stored in the hot water storage tank 103. The first predetermined time is set in advance by calculation or simulation in consideration of, for example, the amount of heat that the fuel cell apparatus 110 can output, the amount of heat that the heat supply apparatus 101 can supply, and the amount of heat that the hot water storage tank 103 can store. Upon receiving the information indicating that the fuel cell apparatus 110 starts up, the second controller 121 may reduce the output of the heat supply apparatus 101 the first predetermined time before the start-up time. As mentioned above, reducing the output of the heat supply apparatus 101 includes stopping the heat supply apparatus 101. Accordingly, there is a case where the second controller 121 reduces the operating time of the heat supply apparatus 101 by controlling the heat supply apparatus 101 to stop the first predetermined time before the start-up of the fuel cell apparatus 110.

Further, when the creation of the operation plan of the fuel cell apparatus 110 has been completed, the first controller 120 may determine and transmit the first predetermined time and the start-up time of the fuel cell apparatus 110 to the second controller 121. In this case, the second controller 121 may create an operation plan in consideration of an operation period of the heat supply apparatus 101, which is set by a user, and the first predetermined time and the start-up time, which are sent from the first controller 120. For example, the second controller 121 may perform control such that the output of the heat supply apparatus 101 in a period during which the fuel cell apparatus 110 operates becomes less than that in a period during which the fuel cell apparatus 110 does not operate (such control includes stopping the heat supply apparatus 101). Still further, the operation plan of the fuel cell 110 may be such that the creation of the operation plan of the fuel cell apparatus 110 is completed at the start of each unit time that defines each cycle of the repeated operation of the fuel cell apparatus 110. The “unit time” is a period such as one day, one week, ten days, or one month. The first controller 120 may transmit a stop time of the fuel cell apparatus 110 to the second controller 121 in addition to the first predetermined time and the start-up time. Further, in a case where such control is performed, the first predetermined time may be set to be shorter than the unit time (the unit time is, for example, one day).

While the fuel cell apparatus 110 is generating electric power, the first controller 120 may control the output of the fuel cell apparatus 110 in accordance with the amount of electric power usage measured by the power load measuring unit, or may control the fuel cell apparatus 110 to operate with rated output.

The first controller 120 may determine the start-up time and the stop time such that, in a unit time, the fuel cell apparatus 110 generates heat in an amount that is equivalent to the amount of heat consumed in the unit time. The amount of heat consumed in the unit time is measured by the thermal load measuring unit. If the amount of heat measured by the thermal load measuring unit is greater than the amount of heat that can be supplied by the fuel cell apparatus 110, the first controller 120 may operate the fuel cell apparatus 110 with rated output which is the maximum output.

The first controller 120 may be configured to be able to control the second controller 121 to change the operation period of the heat supply apparatus 101. In this case, for example, if the fuel cell apparatus 110 can cover a thermal demand that is to arise during an operation period of the heat supply apparatus 101, the operation period being set by a user, then at least one of the start-up time and the stop time of the heat supply apparatus 101 may be changed such that the operating time of the heat supply apparatus 101 is reduced, or the heat supply apparatus 101 may be controlled not to operate. This makes it possible to extend and assuredly secure the operating time of the fuel cell apparatus 110 which is highly energy efficient.

The above description describes a configuration where the hot water storage tank 103 is supplied with heat from two apparatuses that are the fuel cell apparatus 110 and the heat supply apparatus 101. However, as an alternative, another heat supply apparatus may be added and the hot water storage tank may be supplied with heat from three or more apparatuses. In this case, when the fuel cell apparatus 110 is started up, control may be performed such that the outputs of the heat supply apparatuses other than the fuel cell apparatus 110 are reduced.

The power generation system, its components, specific individual steps of the power generation system operating method, etc., described in the working example are suitably applicable to each of the above-described embodiments.

(Another Aspect)

Hereinafter, power generation systems according to another aspect of the present invention are described.

A first power generation system according to the other aspect includes: a fuel cell apparatus configured to generate electric power with use of a fuel gas and an oxidizing gas, and to supply the electric power and heat; a hot water storage tank configured to store water that has absorbed the heat of the fuel cell apparatus; a heat supply apparatus configured to supply heat to the water in the hot water storage tank; a first controller configured to control at least start-up and stop of the fuel cell apparatus in accordance with a predetermined operation plan of the fuel cell apparatus; a second controller configured to control at least start-up and stop of the heat supply apparatus in accordance with a predetermined operation plan of the heat supply apparatus. The second controller is configured to also control the output of the heat supply apparatus, and to reduce the output of the heat supply apparatus in a case where the second controller has received, from the first controller, information indicating that the fuel cell apparatus starts up.

According to the above configuration, the occurrence of a situation where the hot water storage tank becomes a full storage state and thereby electric power generation cannot be performed can be suppressed in a case where a fuel cell apparatus with higher energy efficiency is started up when hot water heated by exhaust heat from the fuel cell apparatus and hot water heated by exhaust heat from the heat supply apparatus are to be stored in the same hot water storage tank. Accordingly, the operating time of the fuel cell apparatus can be secured assuredly.

A second power generation system according to the other aspect may be configured such that the second controller is configured to control the output of a co-generation unit to be less than an output determined by the operation plan of the heat supply apparatus in a case where the second controller has received from the first controller the information indicating that the fuel cell apparatus starts up.

A third power generation system according to the other aspect may be configured such that, in the second power generation system according to the other aspect, the first controller is configured to transmit the information indicating that the fuel cell starts up to the second controller before the fuel cell starts up.

A fourth power generation system according to the other aspect may be configured such that, in the second power generation system according to the other aspect, the first controller is configured to transmit the information indicating that the fuel cell starts up to the second controller a first predetermined time before the fuel cell starts up.

A fifth power generation system according to the other aspect may be configured such that, any one of the first to fourth power generation systems according to the other aspect further includes a load measuring unit configured to measure the amount of electric power and the amount of heat that have been consumed by a consumer provided with the fuel cell apparatus. In the fifth power generation system, the first controller may be configured to control the fuel cell apparatus to generate heat in an amount that is equivalent to the amount of heat measured by the load measuring unit, and the second controller may be configured to control the heat supply apparatus such that the heat supply apparatus operates in an operation period set by the consumer.

A sixth power generation system according to the other aspect may be configured such that, in any one of the first to fifth power generation systems according to the other aspect, the second controller is configured to control the heat supply apparatus such that the heat supply apparatus operates in an operation period set by the consumer, and the first controller is configured to be able to control the second controller to change the operation period.

From the foregoing description, numerous modifications and other embodiments of the present invention may be made by one skilled in the art. Therefore, the foregoing description should be interpreted only as an example and is provided for the purpose of teaching the best mode for carrying out the present invention to one skilled in the art. The structural and/or functional details may be substantially altered without departing from the spirit of the present invention.

INDUSTRIAL APPLICABILITY

The power generation system according to the present invention is useful, for example, as a power generation system in which a fuel cell apparatus and a heat supply apparatus are configured to supply heat to the same hot water storage tank and which makes it possible to reduce a possibility of decrease in energy efficiency.

REFERENCE SIGNS LIST

-   -   10 hot water storage tank     -   20 fuel cell apparatus     -   30 heat supply apparatus     -   40 controller     -   41 first controller     -   42 second controller     -   46 power load measuring unit     -   47 thermal load measuring unit     -   48 detector     -   100 power generation system     -   101 heat supply apparatus     -   103 hot water storage tank     -   105 consumer     -   106 first heat transmission mechanism     -   107 second heat transmission mechanism     -   109 operating unit     -   110 fuel cell apparatus     -   111 fuel cell     -   120 first controller     -   121 second controller     -   130 power generation system     -   140 power generation system     -   150 power generation system     -   160 power generation system 

1. A power generation system comprising: a hot water storage tank configured to store hot water; a fuel cell apparatus configured to generate electric power with use of a fuel gas and an oxidizing gas, and to supply heat to the hot water storage tank and output the electric power; a heat supply apparatus provided separately from the fuel cell apparatus and configured to supply heat to the hot water storage tank; and a controller configured to operate the fuel cell apparatus in accordance with a predetermined first operation plan, and to operate the heat supply apparatus in accordance with a predetermined second operation plan, such that an operation of the heat supply apparatus is independent of an operation of the fuel cell apparatus, wherein in accordance with the operation of the fuel cell apparatus, the operation being performed in accordance with the first operation plan, the controller performs second operation plan change control to reduce an output of the heat supply apparatus to be less than an output determined by the second operation plan in such a manner as to: prevent the hot water storage tank from becoming a state of being unable to absorb heat supplied from the fuel cell apparatus due to receiving heat that the heat supply apparatus supplies to the hot water storage tank through the operation of the heat supply apparatus in accordance with the second operation plan; and allow heat to be supplied from the fuel cell apparatus to the hot water storage tank through the operation of the fuel cell apparatus in accordance with the first operation plan.
 2. The power generation system according to claim 1, wherein the second operation plan change control is to reduce the output of the heat supply apparatus when the fuel cell apparatus starts up.
 3. The power generation system according to claim 2, wherein the controller includes: a first controller configured to store the first operation plan and to start up and stop the fuel cell apparatus in accordance with the stored first operation plan; and a second controller configured to store the second operation plan and to operate the heat supply apparatus in accordance with the stored second operation plan, the first controller is configured to transmit a signal indicating that the fuel cell apparatus starts up, and the second operation plan change control is that, in a case where the second controller has received the signal indicating that the fuel cell apparatus starts up, the second controller reduces the output of the heat supply apparatus.
 4. The power generation system according to claim 3, wherein the signal indicating that the fuel cell apparatus starts up is transmitted at a point that is a first time before the fuel cell apparatus starts up.
 5. The power generation system according to claim 3, wherein the signal indicating that the fuel cell apparatus starts up is transmitted when the fuel cell apparatus starts up.
 6. The power generation system according to claim 2, comprising a detector configured to detect a start-up of the fuel cell apparatus and to transmit a signal indicating that the start-up of the fuel cell apparatus has been detected, wherein the controller includes: a first controller configured to store the first operation plan and to start up and stop the fuel cell apparatus in accordance with the stored first operation plan; and a second controller configured to store the second operation plan and to operate the heat supply apparatus in accordance with the stored second operation plan, and the second operation plan change control is that, in a case where the second controller has received the signal indicating that the start-up of the fuel cell apparatus has been detected, the second controller reduces the output of the heat supply apparatus.
 7. The power generation system according to claim 1, wherein the second operation plan change control is that, in a case where the first operation plan has been changed, the controller changes the second operation plan based on the changed first operation plan.
 8. The power generation system according to claim 7, wherein the controller includes: a first controller configured to store the first operation plan and to start up and stop the fuel cell apparatus in accordance with the stored first operation plan; a second controller configured to store the second operation plan and to operate the heat supply apparatus in accordance with the stored second operation plan, the first controller is configured to transmit information about the changed first operation plan in the case where the first operation plan has been changed, and the second operation plan change control is that the second controller changes the second operation plan when the second controller has received the information about the changed first operation plan.
 9. The power generation system according to claim 1, comprising a load measuring unit configured to measure an amount of electric power and an amount of heat that are consumed by a user of the power generation system, wherein the controller: creates the first operation plan based on the amount of electric power and the amount of heat that have been measured by the load measuring unit, and stores the first operation plan; and creates the second operation plan based on an operation period of the heat supply apparatus, the operation period being set by the user, and stores the second operation plan.
 10. A method of operating a power generation system, comprising: generating electric power with use of a fuel gas and an oxidizing gas by operating a fuel cell apparatus in accordance with a predetermined first operation plan, and supplying heat to a hot water storage tank and outputting the electric power; supplying heat to the hot water storage tank by operating, in accordance with a predetermined second operation plan, a heat supply apparatus provided separately from the fuel cell apparatus, such that an operation of the heat supply apparatus is independent of an operation of the fuel cell apparatus; and in accordance with the operation of the fuel cell apparatus, the operation being performed in accordance with the first operation plan, performing second operation plan change control to reduce an output of the heat supply apparatus to be less than an output determined by the second operation plan in such a manner as to: prevent the hot water storage tank from becoming a state of being unable to absorb heat supplied from the fuel cell apparatus due to receiving heat that the heat supply apparatus supplies to the hot water storage tank through the operation of the heat supply apparatus in accordance with the second operation plan; and allow heat to be supplied from the fuel cell apparatus to the hot water storage tank through the operation of the fuel cell apparatus in accordance with the first operation plan. 